PB2634: USE OF N-ACETYLCYSTEINE THERAPY IN PATIENTS WITH RELAPSED REFRACTORY THROMBOTIC THROMBOCYTOPENIC PURPURA
Authors: Ozlem Beyler, Cengiz Demir
Journal: HemaSphere (2023)

Topic: 28. Enzymopathies, membranopathies and other anemias Background: There is limited data on the use of N-acetylcysteine therapy for thrombotic thrombocytopenia in the literature. We would like to present the satisfactory results we obtained in our resistant and relapsed patients. Aims: NAC can be added to PEX and glucocorticoid treatment, especially in unresponsive patients, as a supportive therapy. Methods: Patients who do not respond to plasma exchange therapy and corticosteroids are required additional therapies such as rituximab, and caplacizumab or other immunosuppressive drugs (vincristine vs.). NAC was administered at a dose of 10 g/day with IV infusion in relaps/refractory patients. Results: CASE 1 A 30-year-old female patient has complaints of bruises, blurred vision, dizziness, fever and chills. In the laboratory examination shown in table 1. Plasma exchange treatment and corticosteroid was started at 1 mg/kg per day with a prediagnosis of TTP. Plasma ADAMTS13 activity was 13% and inhibitör level was 0.14 U/mL. The patient was discharged with 48 mg prednol as an outpatient follow-up. 10 days later, platelet 56.000 103/μL and LDH 541 U/L and schistocytes in the peripheral smear were detected in control examinations. Rituximab 375mg/m2 weekly and vincristine 2 mg weekly were added. Because of platelet elevation was not observed, NAC was administered at a dose of 10 g/day with IV infusion. The day after, platelet increased to 179.000 103/μL. NAC treatment was continued for 10 days. The ADAMTS13 level at the 3rd month follow-up was 15% and patient is in a still remission on controls CASE 2 A 33-year-old male patient presented to the emergency department with the complaint of dark urine. Laboratory parametres were at diagnosis in table 1. Plasmapheresis with 1.5 plasma volume and 1 g/day of methylprednisolone for three days was started. On the 5th day, hematological response could not be obtained, so the PEX was performed twice a day. Plasma ADAMTS13 activity was 12% and inhibitör level was 0.1 U/mL. The patient was started on a weekly rituximab 375 mg/m2 administration for 4 weeks. Platelet count decreased progressively to 30000-40000 103/μL. This refractory patient was also given 2 mg of vincristine. Since the platelet count was still 37.000 103/μL on the 12th day of PEX, NAC was started at 10g/day as a 10-day treatment. At the second day of NAC treatment, the patient had a rapid increase in platelet count. Complete recovery was achieved in the platelet count on the 4th day of NAC treatment and the patient was successfully discharged. At the 6th month control, adamts13 level was determined as 91%. Summary/Conclusion: We want to contribute to the reporting of effective responses under the limited data on NAC. We used rituximab, vincristine and NAC treatment together in order to prevent complications such as bleeding and neurological findings that may be related to the disease in our relapsed/refractory patients who did not respond to plasma exchange and steroids. The fact that we had a faster platelet response than the expected duration of action in rituximab and vincristine treatment suggested that this response was due to the effect of NAC treatment. We think that this treatment option, which has both a low cost and a safe side-effect profile, should be among the treatment options for patients with relapsed/refractory TTP, especially in centers where it is difficult to access expensive agents such as caplasizumab.Keywords: Thrombocytopenia, Thrombotic thrombocytopenic purpura (TTP), ADAMTS13